Researchers reveal why people suddenly become more frail at 70. They discovered a “catastrophic change” in the composition of blood cells and paved the way for new therapies to slow down the aging process.
Cambridge researchers have discovered a process that leads to a ‘catastrophic’ change in blood composition with age, increasing the risk of blood cancer and anemia and reducing the effectiveness of white blood cells at fighting infection.
Scientists believe similar changes occur in all organs of the body, from the skin to the brain, which could explain why people often age in good health for decades before experiencing a more rapid decline in their 70s or 80s.
“The exciting thing about this work is that there could be a number of common processes,” explains Dr. Peter Campbell, lead author of the study and head of the Cancer, Aging and Somatic Mutation Unit at the Sanger Institute in Cambridge. “Ultimately the goal would be to slow or intervene in the aging process, but at least we see a way to use it to measure biological age.” »
A set of processes at work
Aging is a complex process, but many scientists have suggested that the gradual accumulation of mutations in cells gradually impairs the body’s ability to function properly. The latest research suggests that this reasoning is flawed or incomplete at best, instead blaming the “selfish” cells that become dominant as we age.
In collaboration with scientists from the Wellcome-MRC Cambridge Stem Cell Institute, Dr. Campbell and his colleagues studied blood cells from people of all ages, from newborns to those in their seventies and octogenarians. They found that adults under the age of 65 had a wide range of red and white blood cells produced by a diverse population of 20,000 to 200,000 different types of stem cells in their bone marrow.
Sudden collapse of the supply of stem cells
For those over 65, the picture was radically different. About half of their blood cells came from just 10 or 20 separate stem cells, greatly reducing the diversity of the person’s blood cells, with consequences for their health.
In their article, published in the journal Nature, the researchers explain that most of these changes are harmless if the stem cells involved in blood formation mutate over time. Problems arise, however, when rare “pilot” mutations accelerate the growth of stem cells, often producing lower-quality blood cells in return. By the time a person is in their 30s or 40s, the growth advantage of aberrant stem cells makes little difference, but by the age of 70, these fast-growing cells have come to dominate blood cell production.
“Exponential growth explains why there is such a sudden change in frailty after age 70, why aging strikes at that age,” Campbell said. Faster-growing blood stem cells are linked to blood cancer and anemia, but they also make people less resistant to infections and medical treatments like chemotherapy.
“What we know from other organ systems is that many of the same observations hold true,” Campbell added. Researchers now plan to look for the same process in the skin to understand why aging leads to wrinkles and slower healing.
dr Elisa Laurenti, an assistant professor at the Wellcome-MRC Cambridge Stem Cell Institute and co-principal investigator on the study, said chronic inflammation, smoking, infection and chemotherapy can produce stem cells with cancer-causing mutations.
“We predict that these factors also promote the age-associated decline in blood stem cell diversity,” she said. “It is possible that certain factors can also slow down this process. We now have the exciting challenge of understanding how these newly discovered mutations affect blood function in the elderly so we can learn how to minimize the risk of disease and promote healthy aging. »
With The guard